ABSTRACT: Malaria is a major global health problem for which a viable vaccine is desperately needed. The rationale for the proposed research is an effective vaccine for malaria will alleviate the health and socio-economic burden associated with the disease, especially in the face of growing antimalarial drug resistance. The central motivation for this proposal is that design of immunogens driven by insights from the structure-function analysis of antigens will result in a vertical leap in malaria vaccine development, and is now possible given the recent explosion in technology for structural vaccinology and the structural definition of neutralizing epitopes in key malaria antigens. Guided by strong preliminary data, this proposal will pursue three independent yet complementary specific aims: 1) Design pre-erythrocytic infection-blocking and transmission-blocking vaccines, 2) Develop immunogens to focus the immune responses to neutralizing epitopes in blood-stage parasites, and 3) Combinatorially design a multi-stage, cross-species protective immunogen. The first aim will focus on a unique multi-stage antigen that is conserved in Plasmodium spp. and is required for infection and transmission. The second aim examines two red-cell invasion ligands that are targets for neutralizing antibodies and required for blood-stage growth. The third aim proposes to combine immunogen designs to elicit neutralizing responses to multiple stages of the life cycle simultaneously. These aims will be achieved through structural vaccinology, immuno-parasitology, and therapeutic design of novel vaccines. This proposal is innovative because our integrated and complementary research team is well-suited to test novel concepts in vaccine design for malaria, and apply multi-disciplinary technological innovation to comprehensively design immunogens. The proposed research is significant because more than 200 million people every year suffer from malaria, leading to at least 500,000 deaths and an estimated $12 billion of healthcare-related costs. Between 1,500 and 2,000 cases of malaria occur each year in the United States alone and are reported to the CDC, with ~10% being severe and resulting in death. Prior vaccines for malaria have failed due to antigenic variability, targeting immunodominant but non-neutralizing epitopes of antigens, and focusing solely on a single stage of the life cycle. The proposed research is impactful because the iterative approach will: (1) focus the immune response to existing structurally-defined neutralizing epitopes in malaria antigens by creating epitope scaffold immunogens with flexible backbones, (2) use multiple structurally- defined neutralizing epitopes to provide a multi-pronged protective response, (3) assess neutralization for all stages of the malaria life cycle in established assays and mouse models, (4) utilize functional assays to guide and validate protective immunogenicity of epitope targets, and (5) use structure-based modification of antigens to improve immunogenicity and protection.